Subject: when to create a separate filesystem, even on the same spindle (was: major hier(7) overhauls?)To: None <tech-userlevel@netbsd.org>From: Greg A. Woods <woods@most.weird.com>List: tech-userlevelDate: 01/29/1999 15:21:17

[ On Fri, January 29, 1999 at 15:17:29 (+0000), David Forbes wrote: ]
> Subject: Re: major hier(7) overhauls?
>
> As I see it, whilst everyone has different requirements for their set-up
> and so on, there is at least one good reason why you might want / and /usr
> one different partitions.
>
> I, for one, have everyone's home directory under /usr/home. This means,
> since we don't enforce quotas, any user can fill up the /usr partition.
Actually that's a really good reason for creating a separate /usr/home
partion, and has nothing at all to do with whether / and /usr should be
separate partitions or even separate hierarchies. ;-)
The same goes for /tmp, /var, /var/log, /var/mail, /var/spool/news, or
whatever your application demands: You should create a separate
partition to hold files of a given classification if those files might
either themselves grow with wild abandon and impact the operation of
other subsystems, or might themselves be impacted by unwieldy growth of
other filesystems. Once you've got this part figured out then, and only
then, should you re-visit how filesystems are distributed over different
spindles in order to balance their I/O load. Of course properly
balancing the I/O load suggests measuring it first, and so far as I know
there's not yet any way to separately measure the I/O stats for various
filesystems on the same spindle (ala UNIX SysV's "sadp").
In a classic multi-user, general purpose, "shell" machine you'd probably
want at least separate /var, /var/mail, and /var/spool/news filesystems
so that too much mail or too much news didn't stop system logging, etc.
--
Greg A. Woods
+1 416 218-0098 VE3TCP <gwoods@acm.org> <robohack!woods>
Planix, Inc. <woods@planix.com>; Secrets of the Weird <woods@weird.com>